Warning signs showing Marine A's unit were suffering from 'psychological strain and fatigue' were missed by senior officers in Afghanistan, a Royal Navy review has found.
Alexander Blackman - known as Marine A - is serving a life sentence for murdering a wounded Afghan insurgent.
But the former Royal Marine who was based 42 Commando in Plymouth has now been given the right to appeal his conviction after the presentation of new evidence.
His legal team say he was suffering from post-traumatic stress disorder while in Afghanistan.
An internal review carried out by the Royal Navy into the circumstances surrounding the killing in 2011 has identified a series of factors which contributed to the incident.
An 'overly aggressive' culture by 42 Commando
'Moral disengagement' on the part of Sgt Blackman and his colleagues.
Face-to-face supervision was insufficient to identify a number of warning signs.
Inadequate support from the chain of command
The report, which was released by the Ministry of Defence, reveals another officer was forced to take over commanding duties at short notice, after the original was injured.
He had not therefore been prepared for the role and faced a considerable challenge in taking up this command in a demand area of operations.
Following the change concerns over 42 Commandos approach - with claims from many it was "overly aggressive" were "identified to, and by, the Brigade Commander".
But, after an investigation, it was judged the approach was appropriate in the circumstances.
Face-to-face supervision [by the new commanding officer] ...was insufficient to identify a number of warning signs that could have indicated they were showing evidence of moral regression, psychological strain and fatigue.
The report continues by saying Sgt Blackman "allowed professional standards to slip to an unacceptably low level", with his poor leadership a "significant contributory factor" in the way the insurgent was treated.
But, that many in his patrol did not question his orders, or challenge his actions, because of his rank.
It also recognised the difficulty that Royal Marines face dealing with enemies after engaging in conflict.
The difficulty experienced by Sgt Blackman in changing from a mindset which required him to kill an enemy to one which accepted having to administer first aid to an enemy in order to try to save his life, was a contributory factor in his treatment of the insurgent.